The invention relates to a holding part for PTC components with an insulating frame and at least one contact plate.
PTC heaters generally have several juxtaposed PTC components preferably arranged in a row and covered by common contact plates, on whose sides remote from the PTC components are optionally arranged insulating plates. This arrangement is held together in any appropriate way, e.g. by clips, terminal strips, inserting in an envelope and the like. Reference is made in exemplified manner to DE-OS 28 45 965, DE-OS 28 45 894 and DE-OS 29 48 591.
After joining together the PTC components on a contact plate and applying the further contact plate, it is very difficult to handle this structure, because there is a risk of the PTC components laterally slipping out between the two plates before introduction into a casing, or before they are reliably held together by a clamping device.
The aim underlying the present invention essentially resides in a holding part of PTC components for reliably holding providing the PTC components prior to the assembly of the heating arrangement in such a way that they cannot drop out of a sandwich arrangement.
According to the invention this problem is solved by a holding part and an insulating frame, as well as at least one contact plate in that the latter is firmly connected to the insulating frame. In order to achieve a reliable holding of the PTC components during handling, it is not sufficient to have an insulating frame surrounding the narrow sides of the PTC components because, even if a substrate is held against the same from below, e.g. in the form of a contact plate, there is a risk of the insulating frame and the substrates sliding relative to one another, so that once again a single PTC component can drop out of the frame. Thus, according to the invention, the contact plate and insulating frame are firmly interconnected. The term firmly interconnected here means that they cannot be detached without considerable effort and in particular that they cannot be loosened from one another by chance or slide relative to one another. It would fundamentally also be possible to use a threaded coupling. However, preferably the contact plate is riveted in the vicinity of one of its ends to the insulating frame. The firmly fitted contact plate is positioned on one side of the frame, so that the individual PTC components can be inserted in the frame part from the opposite side and are prevented from dropping out by the contact plate. The further contact element, such as a further contact plate or a profile contact body with a U-shaped cross-section can then be placed on the side of the frame and the inserted PTC components facing the contact plate firmly connected to the frame. It is then possible to position further cover elements, such as stable cover plates or the like which protect the insulating member up to the time of further assembly, namely the optional placing of insulating plates on the contact plate. According to a further development of the holding part, a connecting tongue is riveted to the contact plate and/or a contact tongue is constructed in one piece with the contact plate. If the contact plate is already firmly connected to the insulating frame, it is then also appropriate to construct in one piece therewith a connecting tongue, namely that connected to the contact plate and/or to firmly connect it, e.g. by riveting to the insulating frame.
If a relative pivoting of frame and contact plate could also be prevented by two rivets, which are either juxtaposed in one end region or are in each case located at one end region, then it is advantageous to prevent pivoting of that end of the contact plate which is not firmly connected to the insulating frame and also to prevent any bending out of its plane, but not to completely fix the same, so that the end can perform compensating movements, e.g. under compressive forces and temperature changes. In order to achieve this, according to another preferred development, on the end of the insulating frame opposite to the fixed connection between the contact plate and the insulating frame is formed a clip raised out of the plane thereof and which engages over the contact plate end opposite to the fixing point and in particular the contact plate is free between its end regions.
In order to prevent a giving way or yielding of the contact plate under compressive forces exerted during the further assembly of a PTC heater, to ensure a good heat transfer and therefore to obtain the same, according to a preferred development the contact plate is made from flexible sheeting. It is then preferred that the contact plate is bent in convex manner and pretensioned with respect to the frame part. As a result in the case of locally exerted forces, i.e. not exerted over the entire length of the frame and contact plate and which essentially act in the central region, an adequate pressing action is obtained and therefore a sufficiently good contact between the contact plate and the PTC components over the entire length.
According to a further development in the vicinity of the fixing point on the frame side facing the contact plate are provided cams extending out of the plane thereof. It is thus possible to prevent an axial displacement of insulating plates resting on the contact plate side remote from the frame. According to another construction the frame has transverse webs. As a result the individual PTC components can be individually grasped and received in recesses within the frame part.
The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein show: